The present invention relates generally to electrical connectors and more particularly to electrical terminal blocks for connecting wire pairs.
Electrical terminal blocks (also commonly referred to as terminal junction blocks, junction blocks, or barrier blocks) are well known and widely used in commerce as devices for safely, conveniently and efficiently connecting together one or more pairs of wires or cables. For example, electrical terminal blocks are commonly used in the telecommunications industry to provide convenient and compact means for connecting telephone customer service wires (i.e., the “service” side) to telephone exchange distribution cables (i.e., the “exchange” side). Specifically, an electrical terminal block used in the telecommunications industry typically includes a plurality (e.g., 4, 6, 8, 10, 12, 24, etc.) of interconnected terminal pairs which can be used to connect each individual distribution cable wire on the exchange side to a corresponding individual service wire on the service side.
One type of electrical terminal block (also referred to herein simply as a terminal block) which is well known and widely used in commerce includes a unitary, block-shaped base which is constructed out of an insulating material, such as plastic. The base is typically shaped to include a plurality of laterally disposed, equidistantly spaced partitions which extend orthogonally upward from its top surface. Furthermore, a plurality of parallel bus bars are laterally disposed across the top surface of the base, with one bus bar being disposed between each pair of successive partitions. Each bus bar is constructed of an electrically conductive material (e.g., nickel plated brass or nickel plated steel), wherein adjacent bus bars are electrically insulated from one another by the base partition positioned therebetween.
In use, a pair of wires are electrically connected together using a terminal block in the following manner. Specifically, a first wire (e.g., the service side wire) is electrically connected to one end of a bus bar by any number of different termination means (e.g., using a metal screw, metal eyelet or solder terminal). The second wire (e.g., the exchange side wire) is electrically connected to the opposite end of the same bus bar using any similar termination means. With each wire connected to the same conductive bus bar, an electrical path is established between the two wires, thereby effectively creating an electrical connection therebetween. As can be appreciated, additional wire pairs can be connected together in a similar manner using the unused bus bars on the terminal block to complete the necessary electrical connections between the service side wires and the exchange side wires. It should be noted that, in this manner, a terminal block serves as an organized, miniaturized and reliable means for connecting multiple pairs of electrical wires, which is highly desirable.
Having utilized a terminal block to complete the necessary connections between service side wires and exchange side wires, the terminal block, in turn, is often provided with means for securing the terminal block to a fixed object such as a support panel (e.g., a wooden panel on which a fuse box is mounted). In this manner, the terminal block can be positioned at a location which would minimize inadvertent contact.
Accordingly, terminal blocks of the type described above are typically provided with either panel mount means or Deutsche Industrie-Normen (DIN) rail mount means for retaining the terminal block onto a support panel. A panel mount terminal block is typically provided with a bore or slot at each end which enables the terminal block to be directly affixed onto a support panel using a conventional fastener (e.g., bolt or screw). A DIN rail mount terminal block is typically provided with means for snap-fitting the terminal block onto a metal bracket (i.e., a DIN rail) which, in turn, is affixed onto the support panel by screws.
Terminal blocks of the type described in detail above typically suffer from a few notable drawbacks.
As a first drawback, terminal blocks of the type described above are often used in commerce to actively electrically connect multiple (e.g., 10, 12 or 24) pairs of electrical wires. As a result, a considerable amount of electrical current often continuously passes through the bus bars of the terminal block. Accordingly, it has been found that electricians (or other suitable personnel) who frequently access the terminal block are susceptible to high (and often potentially fatal) levels of electrical shock because the terminal block is equipped with no means for temporarily shunting electrical charge present in the bus bars, which is highly undesirable.
As a second drawback, terminal blocks of the type described above are often provided with a plurality of laterally disposed parallel bus bars which are mounted on the top surface of the terminal block base in a substantially exposed manner. As a result, the top surface of each bus bar is rendered highly susceptible to inadvertent contact by any individual who works in the vicinity of the terminal block. As noted above, because each bus bar serves as a conductive path between a pair of wires, inadvertent contact with a bus bar can result in serious physical injury or death, which is highly undesirable.
As a third drawback, terminal blocks of the type described above are often provided with a plurality of ring lug receiving terminals, each terminal being designed so as to require a relatively time consuming and labor intensive process for connecting the ring lug of a wire thereto. Specifically, in order to couple a ring lug to such a terminal, a multiplicity of steps are required. First, a screw needs to be completely withdrawn (i.e., unscrewed) from a threaded bore formed in a bus bar. Second, the free end of the wire (or, in the alternative, a ring lug formed onto the free end of the wire) is disposed over the threaded bore in the bus bar. Third, while maintaining the wire in position against the bus bar, the metal screw is screwed back into the threaded bore so as to secure the wire in electrical connection with the bus bar. As can be appreciated, this three-step process for connecting each wire to an associated bus bar requires a considerable amount of manual dexterity and time, which is highly undesirable.
As a fourth drawback, terminal blocks of the type described above are typically manufactured with either panel mount or DIN mount capabilities. However, at the time of purchase, potential customers are often not readily aware which mounting type of terminal block will be required. Because conventional terminal blocks can not be readily converted between panel and DIN rail mount capabilities, the consumer often purchases a terminal block with the wrong type of mounting capability, which is highly undesirable.
As a fifth drawback, DIN rail mount terminal blocks of the type described above are typically designed to slide along the length of a DIN rail when snap-mounted thereon. Accordingly, after one or more DIN rail mount terminal blocks have been mounted onto a DIN rail, a pair of end pieces (i.e., bookends) are fixedly mounted on the DIN rail directly outside the terminal blocks. In this capacity, the end pieces preclude the one or more terminal blocks positioned therebetween from sliding along the DIN rail. Although useful in fixing the position of the one or more terminal blocks on the DIN rail, these types of end pieces are often somewhat bulky in size. As a result, the end pieces limit the number and/or size of terminal blocks which can be mounted along the length of a standard DIN rail, which is highly undesirable.